SPANphos
Encyclopedia
SPANphos is an organophosphorus compound used as a ligand in organometallic
and coordination chemistry. This compound is a rare example of a trans-spanning ligand
and rigidly links mutually trans coordination sites. By virtue of its chiral backbone that forms a chiral cavity over the face of a square planar complexes, e.g. in MCl2(SPANphos) (M = Pd, Pt).
and acetone
. The spirane is brominated with N-bromosuccinimide
, and the resulting dibromide is metalated with n-BuLi
. Treatment of the resulting dilithio derivative with chlorodiphenylphosphine
completes the synthesis.
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...
and coordination chemistry. This compound is a rare example of a trans-spanning ligand
Trans-spanning ligand
Trans-spanning ligands are bidentate ligands that can span opposite sites of a complex with square-planar geometry. A wide variety of ligands that chelate in the cis fashion already exist, but very few can link opposite vertices on a coordination polyhedron...
and rigidly links mutually trans coordination sites. By virtue of its chiral backbone that forms a chiral cavity over the face of a square planar complexes, e.g. in MCl2(SPANphos) (M = Pd, Pt).
Synthesis
This C2-symmetric trans-diphosphine is synthesized from inexpensive reagents. In the first step 4,4,4',4',6,6'-hexamethyl-2,2'-spirobichroman is prepared via an acid-catalyzed reaction between p-cresolP-Cresol
p-Cresol, also 4-methylphenol, is a phenol, with formula C6H4.It is a positional isomer; the other two are m-cresol and o-cresol. P-cresol is a major component in pig odor. . For more information see cresol. 4-methylphenol is a component in human sweat. It is a component of human odour attractive...
and acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
. The spirane is brominated with N-bromosuccinimide
N-Bromosuccinimide
N-Bromosuccinimide or NBS is a chemical reagent which is used in radical substitution and electrophilic addition reactions in organic chemistry. NBS can be considered a convenient source of cationic bromine.-Preparation:...
, and the resulting dibromide is metalated with n-BuLi
Butyl lithium
Butyllithium may refer to one of three isomeric organolithium reagents used in chemical synthesis:*n-Butyllithium, abbreviated BuLi or nBuLi*sec-Butyllithium, abbreviated sec-BuLi or sBuLi...
. Treatment of the resulting dilithio derivative with chlorodiphenylphosphine
Chlorodiphenylphosphine
Chlorodiphenylphosphine is an organophosphorus compound with the formula 2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is useful reagent for introducing the Ph2P group into...
completes the synthesis.
